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Explain how Traefik integrates with OpenTelemetry for distributed tracing?

Traefik can act as an OpenTelemetry-instrumented component in a request's trace, creating spans for the routing, middleware, and proxying work it performs, and propagating trace context headers to the backend it forwards the request to.

tracing:
  otlp:
    http:
      endpoint: "http://otel-collector:4318/v1/traces"

Once configured with an OTLP endpoint, Traefik exports spans for each request it handles, tagged with attributes like the matched router, service, and response status, and, critically, injects the trace context (trace ID, span ID) into the outgoing request headers so the backend's own instrumentation can continue the same trace rather than starting a new one.

This lets an operator follow a single request end to end in a tool like Jaeger or Grafana Tempo: entering Traefik, passing through its middleware chain, arriving at the backend, and any downstream calls that backend makes, all stitched into one trace instead of disconnected fragments per service.

What does Traefik inject into the outgoing request when tracing is enabled?
Traefik's tracing spans are typically tagged with:

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Erlang

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